Nonnegative elements of subgroups of

We give a method to compute all nonnegative integer solutions of a homogeneous system of linear equations. We use this method to provide an algorithm to compute all nonnegative integer solutions of homogeneous systems of equations having some of the equations in congruences.     

Positive Periodic Solution of a Periodic Cooperative Model with State Dependent Delays

By using the continuation theorem of coincidence degree theory, sufficient conditions are obtained for the existence of positive periodic solution for the periodic cooperative system with state dependent delays where r i , a i , c i , i = 1, 2 are positive continuous y -periodic functions, b i , i = 1, 2 are nonnegative continuous y -periodic functions, and ij , i = 1, 2; j = 1, 2, 3 are nonnegative continuous functions and y -periodic with respect to their first argument.     

Une version non linéaire du théorème de représentation de Riesz

We give a necessary and sufficient condition for a nondecreasing functional on the set of the continuous nonnegative functions on a compact metrizable space to have a unique extension as a functional Choquet's capacity on the set of Borel nonnegative functions.     

The determinability of compacts by lattices of ideals and congruences of semirings of continuous [0, 1]-valued functions on them

We consider an idempotent semiring of continuous [0, 1]-valued functions defined on a compact X with the usual multiplication and addition max. We prove the determinability of X by the lattice of ideals and the lattice of congruences of the indicated semiring.     

The error norm of Gauss-Radau quadrature formulae for Chebyshev weight functions

In certain spaces of analytic functions the error term of the Gauss-Radau quadrature formula relative to a (nonnegative) weight function is a continuous linear functional. We compute or estimate the norm of the error functional for any one of the four Chebyshev weight functions.     

Nonnegative solvability of linear equations in certain ordered rings

In the integers and in certain densely ordered rings that are not fields, projections of the solution set of finitely many homogeneous weak linear inequalities may be defined by finitely many congruence inequalities, where a congruence inequality combines a weak inequality with a system of congruences. These results extend well-known facts about systems of weak linear inequalities over ordered fields and imply corresponding analogues of Farkas' Lemma on nonnegative solvability of systems of linear equations.

     

Combinatorial interpretations of congruences for the spt-function

Let spt(n) denote the total number of appearances of the smallest parts in all the partitions of n. In 1988, the second author gave new combinatorial interpretations of Ramanujan’s partition congruences mod 5, 7 and 11 in terms of a crank for weighted vector partitions. In 2008, the first author found Ramanujan-type congruences for the spt-function mod 5, 7 and 13. We give new combinatorial interpretations of the spt-congruences mod 5 and 7. These are in terms of the same crank but for a restricted set of vector partitions. The proof depends on relating the spt-crank with the crank of vector partitions and the Dyson rank of ordinary partitions. We derive a number of identities for spt-crank modulo 5 and 7. We prove the surprising result that all the spt-crank coefficients are nonnegative.     

一类不可微优化的Fritz-John条件

基于星形集空间的性质,定义一类星形可微函数.这类函数是方向可微的,其方向导数可以表示成两个正齐次非负连续函数之差,其星形微分为一星形集对.对于含有不等式约束条件的星形可微优化问题,给出一个Fritz-John形式的最优性必要条件.     

Expansion over a system of shifts of pyramidal functions

A method for approximation of functions of two variables by a linear combination of nonnegative piecewise linear functions with a compact support is presented. The crucial idea of this method consists in an “integral” calculation method for the coefficients. The accuracy of the approximation in the spaces of continuous and integrable functions is proved to have the same order as the best approximation by piecewise linear functions.     

Congruences for 2 F 1 Hypergeometric Functions Over Finite Fields

In a recent paper, Ono and Penniston proved a family of congruences for ₃ F ₂ hypergeometric functions over finite fields. They use the relationship between these functions and the arithmetic of a certain family of elliptic curves to obtain their congruences. Here we prove analogous congruences for ₂ F ₁ hypergeometric functions.     

On Factorizations of Smooth Nonnegative Matrix-Values Functions and on Smooth Functions with Values in Polyhedra

We discuss the possibility to represent smooth nonnegative matrix-valued functions as finite linear combinations of fixed matrices with positive real-valued coefficients whose square roots are Lipschitz continuous. This issue is reduced to a similar problem for smooth functions with values in a polyhedron. The work was partially supported by NSF Grant DMS-0653121.     

A Factorization Problem on a Smooth Two-Dimensional Surface

Mathematical Notes - Given a continuous complex-valued function $$a$$ and nonnegative functions $$\rho_1$$ and $$\rho_2$$ on a two-dimensional smooth connected closed surface such that...     

A weak condition of globally asymptotic stability for neural networks

In this work we consider a general class of continuous activation functions which may be neither bounded nor differentiable; however, many sigmoidal functions are included as special cases. With this class of activation functions we give a result on asymptotic stability for neural networks under a weak condition of nonnegative definiteness. Then we show that differentiability is a condition for its exponential stability.     

Operator log-convex functions and operator means

We study operator log-convex functions on (0, ∞), and prove that a continuous nonnegative function on (0, ∞) is operator log-convex if and only if it is operator monotone decreasing. Several equivalent conditions related to operator means are given for such functions. Operator log-concave functions are also discussed.     

On Completeness and Minimality of Random Exponential System in a Weighted Banach Space of Functions Continuous on the Real Line

In this paper, the completeness and minimality properties of some random exponential system in a weighted Banach space of complex functions continuous on the real line for convex nonnegative weight are studied. The results may be viewed as a probabilistic version of Malliavin's classical results.     

Potential Theory of Special Subordinators and Subordinate Killed Stable Processes

In this paper we introduce a large class of subordinators called special subordinators and study their potential theory. Then we study the potential theory of processes obtained by subordinating a killed symmetric stable process in a bounded open set D with special subordinators. We establish a one-to-one correspondence between the nonnegative harmonic functions of the killed symmetric stable process and the nonnegative harmonic functions of the subordinate killed symmetric stable process. We show that nonnegative harmonic functions of the subordinate killed symmetric stable process are continuous and satisfy a Harnack inequality. We then show that, when D is a bounded κ-fat set, both the Martin boundary and the minimal Martin boundary of the subordinate killed symmetric stable process in D coincide with the Euclidean boundary ∂D. The research of this author is supported in part by MZOS grant 0037107 of the Republic of Croatia and in part by a joint US-Croatia grant INT 0302167.     

Ramanujan-type congruences modulo 8 for 7- and 23-core partition functions

Recently, Radu and Sellers proved numerous congruences modulo powers of 2 for \( (2k+1)\)-core partition functions by employing the theory of modular forms. In this paper, employing Ramanujan’s theta function identities, we prove many infinite families of congruences modulo 8 for 7-core partition function. Our results generalize the congruences modulo 8 for 7-core partition function discovered by Radu and Sellers. Furthermore, we present new proofs of congruences modulo 8 for 23-core partition function. These congruences were first proved by Radu and Sellers.     

Congruences for arithmetic functions

The Ramanujan Journal - Motivated by congruences for partitions, we study congruences for three well known arithmetic functions: the divisor function d(n), the sum-of-divisors function $$\sigma...     

Excessiveness of harmonic functions for certain diffusions

In an earlier paper⁽⁴⁾ the author has shown that a diffusion process whose potential kernel satisfies certain analytic conditions has all of its excessive harmonic functions, which are not identically infinite, continuous. This paper shows that under these conditions (concerning its potential kernel), the excessiveness of its nonnegative harmonic functions isautomatic.     

Order properties of attractive spin systems

Methods of constructing semigroups of operators describing interacting particle systems are reviewed. A simple proof is given showing the existence of semigroups of operators on the space of bounded Borel measurable functions for nonnegative continuous attractive spin rates along with a proof of the existence of invariant measures for the semigroups so constructed.